GB2058152A - Yarn feeder mechanisms and double cylinder knitting machines having such mechanisms - Google Patents

Abstract

The invention is for a double cylinder knitting machine having a plurality of pivotable feeders 14 with yarn feeding ends movable through arcs from a trap position, through a feed position to a cross-over park position upstream of the feed position and a plurality of rotatable cams and cam followers connected to feeders to impart pivotal movement thereto during a feeder change and means for adjusting the feed positions of the respective feeders, in which the cams and cam followers pivot the feeders upstream of the feed position to an extent sufficient to clear a latchguard and sinkers of the knitting machine before further pivotal movement for cross-over and reaching of the park position, stop means 54 arrest the feeders in predetermined park positions whilst the cam followers are still on an inclined part of the cams and means are provided for making continued motion of the cams ineffective after the feeders have reached the park positions. <IMAGE>

Description

SPECIFICATION Yarn feeder mechanisms and double cylinder knitting machines having such mechanisms DESCRIPTION Field of Invention The invention relates to double cylinder knitting machines and particularly feeder mechanisms therefor. The invention is especially directed to feeder mechanisms for use at main yarn feeding stations.

Background of the Invention Known "main" yarn feeder mechanisms (see British Patent Specification 301,350; 1,009,698) are difficult to adjust, leading to demanding manufacturing and assembly requirements as well as the need for skilled operations in the use and assembly of machines. The detailed arrangements may have to be slightly different for different gauges (needle density), and different cylinder diameters. It may also be necessary to use different drive arrangements (such as cams, cam followers) for different feeders on a particular machine. Adjustments of a delicate nature may have to be effected for different kinds of knitted articles (whether broad-ribbed, rib patterned, or jacquard patterned) so as to ensure that the feeders change over reliably.In addition more feeders are required for modern forms of sock finishing, particularly closing of the toe pouch, which require the incorporation of yarns with widely varying characteristics. Additional feeders can sometimes be accommodated only by using special mechanisms.

One particular form of feeder mechanism described in the British Patent Specification 535,946, resembles the construction of the invention superficially but was utilised for the highly specialised purpose of half round striping (knitting different yarns on the top of a foot portion from the yarn in the sole of the foot portion) and required consequential changes in knitting machine arrangement, few of which are described in the British Patent Specification. The feeder mechanism concerned provided a small overlap between ingoing and outgoing yarns and could only pick up in predetermined areas.Verge bits had to be removed at the needles involved in pick up hindering rib knitting; latchguards and sinkers were cut away and the sinkers retracted temporarily upstream of the location where needles picked up the yarn to enable the feeders to move into and out of the feed position with sufficient clearance. The feeders could collide with one another when the mechanism was not properly set up. Overall the arrangement, although it achieved its special objective, led to considerable congestion in the knitting zone at the latchguard and sinkers so hampering further adaptation of the mechanism to different types of knitting machines and to different types of yarn and fabric design. Split cams were used to control feeder motion.The mechanism was regarded as extremely critical in its setting up and use and it fell into dis-use when half-round striping was superseded by other forms of patterning to distinguish the top and sole of foot portions of socks.

It is the object of the invention to provide an improved feeder mechanism. The invention seeks to provide a feeder which both reduces the manufacturing difficulties and enhances the versatility of the feeder in use. It is also the object of the invention to provide a feeder mechanism of simplified construction, capable of simple adjustment and enabling more feeders to be incorporated.

Summary of the Invention The invention uses the basic actuation system of the British Patent Specification 535,946 in that the feeder mechanism has (1) a plurality of pivotable feeders with yarn feeding ends movable through arcs from a trap position, through a feed to a cross-over park position upstream of the feed position and (2) a plurality of rotatable cams and cam followers connected to feeders to impart pivotal movement thereto during a feeder change and (3) means for adjusting the feed positions of the respective feeders. It is to be noted that the pivotal movement is such that the feeder does not clash with the closing needle latches and a movement of the feeders in a radial direction (to clear latches and/or bring a new yarn over the closing needle latches for licking in of the new yarn) is avoided.

According to the invention, the cams and cam followers pivot the feeders upstream of the feed position to an extent sufficient to clear a latchguard and sinkers of the knitting machine before further pivotal movement for cross-over and reaching of the park position, stop means arrest the feeders in predete;mined park positions whilst the cam followers are still on an inclined part of the cams and means are provided for making continued motion of the cams ineffective after the feeders have reached the park positions.

Whereas the British Patent Specification is adapted to give a very short overlap between outgoing and ingoing yarns and the feeders spend only a short time upstream of the feed position during change over, the invention utilises a more gradual feeder movement whereby the feeders move generally through longer arcs, resulting in a longer overlap between ingoing and outgoing yarns and a smooth change-over. As a longer overlap between ingoing and outgoing yarns may be used, the considerable arc through which some of the feeders move, does not lead to the need for a high speed of feeder movement. It may be possible to effect yarn changes at knitting speeds which are higher than usual.By using the invention, the feeder which has the shortest movement to the park position can be arranged to move well clear of the latchguards and sinkers whilst numerous other feeders can be located for parking further upstream without exceeding the range in which yarns will properly feed or feeders wrap around yarns of other feeders.

Consequentially the feeders have a movement at a feed level not only from a feed position downstream for reaching trap positions (as in the British Patent Specification 535,946) but also movement at a common low level upstream of the feed position. The movement must in any case clear the latchguard which may have a lower edge bevelled away to facilitate movement of the feeder at the common feed level with sufficient feeder/latchguard clearance. The bevelled latchguard shape also helps to urge the yarn downward as the feeder moves upstream.

Advantageously the movement is such that the feeders are clear of the sinkers which are projected radially outward at that stage. This helps to ensure that any up or down movement for cross-over does not significantly alter the yarn pick up conditions in the area where the latches close.

In spite of the use of a considerable arc of movement at a common feed level, the feeders can be parked and crossed over within an additional arc upstream of the feed position which is small. By using the stop means a high number of feeders can be parked in separate positions before the full extent of the arc becomes so big that pickup becomes unreliable for the feeder(s) which has the arrest movement upstream. Thus five or six feeders can be accommodated with relative ease and if required it could be feasible to use seven feeders all operating on the same principle. The close packing of the feeders in the park position is maintained, regardless of the precise adjustment of the feeder position. The stop means thus make it possible to provide for a considerable adjustment range without detracting from the close parking arrangement.All the feeders move along the same path past the needles for licking in the yarn. Congestion in this area can be reduced.

Conventionally formed latchguards and sinkers may be employed.

Changes in adjustment alter the period which is spent by the feeders in the park position but do not influence the overall duration of the yarn change operation. Feeders can be adjusted in different senses for proper feeding without influencing their joint operation during feeder change operations.

In a preferred form of the invention the feeders are operated by means of Bowden cables which can be adapted to simultaneously provide feeder position adjustment and compensation for changes in cable dimension. At the same time the cable permits the feeders and cams to be mounted in any desired relative position so enabling good access to the knitting zone to be provided. All adjustment necessary can be effected through the Bowden cables, thus considerably simplifying setting up of the machine compared with older constructions in which a number of separate but inter-related adjustments had to be made. The cable also can function to make continued cam motion ineffective in such a way that the stopping at the park position can be damped.Preferably therefore the followers are connected to the feeders by Bowden cables, the length of the cables is adjustable to compensate for changes in cable length and to adjust the feeder position and one end of a sleeve of the cable is supported by resilient means which constitute the means for making excessive cam induced motion ineffective after the feeders have reached the park positions as a result of travelling up a cam slope. The improvement in operation of the feeder mechanism can thus be achieved whilst simplifying the overall construction.

Suitably further stop means are provided to arrest the feeders in predetermined trap positions, excess motion being avoided by lifting the followers off the cams. Thus both park and stop positions can be determined regardless of feeder position adjustment whilst the feeder in the trap position is under minimal strain. Concurrently with the generally large arc of pivotal feeder movement, the trap positions can be located further downstream of the feed positions than usually. Thus the ingoing yarn passes centrally through the area in which the needle latches close even where the feeders are well upstream in the park positions. This also has the added benefit that the needles facing the trappers can be raised for subsequent knitting and hold the loose ends of yarn on the outside of the needles.The ends may be knitted in at the subsequent station but they are in any event on the inside of the finished sock.

A further benefit is that the feeders may be spaced well apart in the trap positions facilitating access for threading in yarns.

Advantageously the cams and cam followers for at least some of the feeders are the same and the park and trap positions are differentiated by applying a different leverage from the cam followers to the Bowden cables. The cams can be made to serve all or most feeders of a mechanism and indeed the same cams may be used on different gauges and cylinder diameters. The cams can be shaped to alter the dwell period upstream of the feed position which determines the overlap between the ingoing and outgoing yarns.

Preferably the overlap invoives 20 needles approximately which is shorter than the overlap required for many known main feeder mechanisms. The feeders can be moved to the trap position at a low speed substantially matching that of the needles so that little additional yarn is drawn from the feeder before the yarn is cut and trapped.

The British Patent Specification 535,946 used guide plates to superimpose a vertical movement for cross-over and trapping. The invention uses an analogous control which is knownperse but, because the cross-over zone is well upstream of the feed position and substantially clear of the knitting instruments, the tracking can be adapted to optimise feed and pick up conditions and the up/down movement superimposed has less influence on the feeding. Preferably the feed position is adjacent the level of the upper edge of sinkers of the knitting machine and a guide plate is provided for lifting feeders for cross-over after they have moved clear of the latchguard and sinkers.The low feed position enables the needle latches to engage the yarn with increased certainty and the feeder is kept at this secure feeding level for a prolonged period before lifting for cross-over. Even when lifted the bottom edge of the latchguard can guide the yarn and keep the yarn at the secure level. Rib needles can participate in pick-up. Early or late closing of latches due to different yarn tension has little effect on pick-up.

Advantageously the feeders, which have park positions nearer the feed position, are arranged to be lowered after the initial lifting just before reaching the respective park positions so as to be at the original feed level and at least one feeder more remote from the feed position is arranged to be moved upward just before reaching its respective park position. By differentiating the final parking level in this manner wrapping of yarn at the extreme of the arc of feeder movement can be avoided so permitting more feeders to be used than when all feeders park at the same level.

Suitably the feeder parked nearest the feed position is a plating feeder suitable for plating in either direction of reciprocation and the feeder is arranged to be kept at the same level to move into the park position. The plating relationship is thus not disturbed during a feeder change and the mechanism can be used to give joints between fabric knitted by the outgoing and incoming yarns respectively when commencing or ending plating which have a good appearance. Further advantages and preferred features will be apparent from the description of the preferred embodiment.

Drawings Figure 1 is a perspective view from the right hand side of a yarn feeder mechanism on a double cylinder knitting machine of the invention, certain parts being omitted for clarity; Figure 2 is a perspective view from behind of the yarn feeder assembly of the mechanism of Figure 1 showing individual feeders in feed, park and trap positions; Figure 3 is a detailed plan view of an individual feeder of the mechanism of Figure 1; Figure 4 is a detailed view, partly in section, of an actuator assembly of the yarn feeder mechanism of Figure 1; Figure 5 is a detailed view, partly in section, through a trapper assembly of the yarn feeder mechanism of Figure 1; Figure 6 is a schematic plan view showing the respective park, feed and trap positions of the feeders of the mechanism of Figure 1;; Figure 7 is a view of a guide plate assembly for controlling pivotal and up/down movements of the yarn feeders; and Figure 8 is a section through the knitting head showing the relative position of the feeders with respect to knitting instrumentalities when in the feed position.

Description of Preferred Embodiment A double cylinder knitting machine (see Figures 1, 2, 8) has a pair of cylinders 2, 4 mounted on top and bottom bed plates (not shown) by pillars 6 (only one of which is shown). Associated with the cylinders 2, 4 is a yarn feeder mechanism incorporating a pre-assembled yarn feeder assembly and a pre-assembled actuator assembly.

A latchguard 5 (see Figures 2, 8) shields the needles.

The feeder assembly is mounted on a middle bed plate 8 and comprises a base plate 10 pivotably mounted on the plate 8 and carrying a post 12 pivotably mounting six feeders 14; a post 16 supporting one side of a slotted tipping plate 18; a post 20 supporting the other side of the plate 18; and a post 22 supporting devices for pivotting the feeders 14. The posts 12, 20 and 22 are secured at the top by a bracket 24 for extra rigidity. The post 22 also carries a trapper assembly 26.

The actuator assembly (see Figures 1, 4) is mounted on the bottom bed plate and comprises the usual components including a shaft 30 mounting a plurality of cams 31 for operating cam followers 32 for the feeders 1 4 and cams (not shown) and cam followers 34 for the trappers.

Bowden cables 36 connect the feeders 14 to the cam followers 32. The wires 38 of the Bowden cables 36 are held taut by tension springs 40 and 42 acting on the feeders 14 and followers 32 respectively. The sleeves or sheaths 44 of the cables 36 are located at one end on the post 22 and at the other end in sockets 46 in a fixed plate 48 of the actuator assembly. The sockets 46 are adjustable heightwise, can be fixed by nuts 47 and contain compression springs 50 for locating the ends of the sheaths 44.

The individual feeders 14 are thus arranged as shown in Figure 3. The wire 38 pulls the feeding end 52 to the left against the tension of spring 40 to an extent permitted by the adjustable stop screws constituting the stop means 54 in the tipping plate 18. When the wire 38 is relaxed, the feeding end 52 moves to the right to an extent permitted by the slot in the tipping plate 18. Slots in the tipping plate 18, described in detail later, also impart up/down movement to the feeding end about a pin 56. The feeders 14 are pivotably secured by bushes 58 fixed to the post 12 to hold the feeders 14 apart and collars 60 pivotable with respect to the post 1 2 and mounting the respective pins 56.

The cam followers 32 are arranged as shown in Figure 4. The tip 62 of the cam follower 32 is pivoted by the cam 31 to pull the wire 38. The cams 31 for the different feeders 14 are the same.

The respective wires 38 are however attached at different radii (r) to the cam followers 32. The tension spring 42 urges the tip 62 against the cam 31 when the wire 38 is relaxed as the tip 62 moves radially inward to the shaft 30. The cam follower 34 for the trappers is operated in a similar way.

The trapper assembly 26 is as shown in Figure 5. A trapper blade 70 is movable up or down between a front wall 72 of a housing and pressure levers 74 having pressure adjustment screws 76 by means of a T-shaped lever 78 pivotable by the cam followers 34 and Bowden cables 80. A slide 82 and tension spring 84 urge the blade 70 downwards to an extent controllable by the eccentric 86. The trapper blades 70 have recesses at the top for receiving yarn and trapping and cutting it, aided by the guide wire 88.

Operation The cams 31 have such a throw, and the wires 38 are connected to the cam followers 32 at such radii r1 that the feeders 14 are pivotable to provide at least the arcs of motion indicated in Figure 6.

The adjustable stop screws 54 and the extremities of slots in the tipping plate 1 8 are arranged to locate the feeders 14 precisely in the park and trap positions shown in Figure 6, park positions being indicated by P, with the suffix indicating the feeder concerned which have been numbered consecutively starting with the lowermost feeder on the post 12. The trap positions are similarly indicated buy.... . T6. The cams 31 have an intermediate part between the peaks of the lobes and the troughs therebetween for holding the feeders at a feed position indicated at F in Figure 6. The feed position is illustrated in Figure 2 and is generally common to the different feeders, slightly upstream of a V-shaped recess in the latchguard 5.The feed positions can be adjusted individually for each feeder 14 in a circumferential direction by adjusting the sockets 46. Such adjustment does not change the feed and trap positions as will be explained. The positions P1... P8 are within such an arc that the yarn will extend generally tangentially to the cylinders 2,4 and pass through the area in which the latches are closed by old loops. Thus the new yarn is reliably licked into the needle hooks. The path of the closing latches is shown by an inclined dotted line Z in Figure 2.

The tipping plate 1 8 (see Figure 7) has six slots 90 one for each feeder 14. The tipping plate 18 and the feeders 14 are arranged relative to one another so that all feeder ends in the feed position are located at the level shown in Figure 8 over sinkers 92 just at the bottom edge of the latchguard 5. The sinker level is shown by a horizontal dotted line Y in Figure 2. The tipping plate 18 provides a common movement of all the feeders at this level (as shown by distance L1 in Figure 7). This distance includes the feed position F as shown by the line F, the adjustment to either side thereof shown by distance L2, and an additional movement to move the feeders 14 clear of the latchguard 5 and the sinkers of the knitting machine,. prior to any upward movement for reaching the trap positions of the park positions.

The tipping plate 18 differentiates the movement to the park positions P1... P6 in the following way. The lowermost feeder 14 remains at the same level. This feeder is advantageously a plating feeder as shown in Figure 2 suitable for plating during reciprocation. By holding it at the same level and imparting the smallest arc of movement, plating is continued when the feeder moves upstream to the park position. The next four feeders 14 move upward in the same part of the knitting machine and then travel horizontally to different extents for lowering to reach the park positions P2, P3, P4 and P8. Although yarns can pass from one parked feeder below another parked feeder 14, wrapping of yarn around the feeders is avoided as the yarn slides to the front of the feeders 14.The largest arc feeder 14 has an initial horizontal movement in an elevated attitude but is then raised further to reach the park position - P6. Thus although its yarn can run across other feeders 14 in position P1 to P5, it cannot wrap around those feeders. Any lifting only occurs where the resultant change in yarn feed angle is small.

The tipping plate also differentiates the movement to the trap positions Ti to T6 as can be readily understood from Figure 6, 7. As shown in Figure 2 an elastic yarn feeder 94 having a retractable feeding end can be located under the feeders 14 and which may be operated by its own particular control means.

A yarn feeder change is effected in a manner generally known per sue as the two cams 31 of the actuator assembly are moved through an angle to pivot the outgoing feeder 14 to its park position and then move the incoming feeder 14 through the feed position to the park position, lagging behind the outgoing feeder and then move the outgoing feeder to the trap position and the ingoing feeder to the feed position with the outgoing feeder leading the ingoing feeder 14.

Successive stages of this operation can be derived from Figure 4 which shows two cams 31 suitably displaced in stages I through to VI for changing yarns.

Of particular importance are however the end stages of the movement to the park and trap position. Towards the end of the movement to the park position, the feeder 14 engages the stop screw 54. The cam 31 continues to pivot the cam follower 32 but this move is now ineffective, the further shifting of the wire 38 merely resulting in a compression of the spring 50. Towards the end of the movement to the trap position, the feeder 14 engages the end of the respective slot and the cam follower 32 is lifted from the cam 31 as this continues to turn through a small additional angle without effecting the feeders 14.

The adjustment of the feed positions can alter the time at which the feeders arrive at the park positions and hence the lapse of time between the arrival of the outgoing and ingoing feeders.

However the cams 31 are profiled so that the outgoing feeder always arrives before the ingoing feeder and leaves the park position first to overtake the ingoing feeder so that the ingoing feeder trails the outgoing feeder on moving to the feed position by a considerable distance. This applies also when the lowermost feeder replaces the uppermost feeder. In this case the uppermost feeder 14 departs from the park position sufficiently early to move past the lowermost feeder before the latter moves to the feed position.

In the arrangement described, the time spent upstream of the feed position does not vary between feeders 14. What does vary, as explained, if the time spent in the park position (which varies a little depending on the period of time during which the spring 50 is compressed whilst the feeder 14 is in the park position and hence the adjustment at the feed position) and also the time spent at the common feed level which is considerable for the lowermost feeder and relatively short for the uppermost feeder. The cam 31 should be arranged so that the outgoing feeder is about to enter the common feed level before the ingoing feeder leaves the park position.

In this way all eventualities can be accommodated and the precise timing of the movement into and out of the park positions and the common feed level can be ignored in the setting up of the knitting machine.

The relative angle of the cams 31 for ingoing and outgoing yarns can be varied to some extent.

However the time spent by both ingoing and outgoing feeders upstream cannot be made too short as the feeders would then have to move so close together that clashing might take place or cams would have to be specially cut for the individual feeders. Thus the overlap must in practice be in excess of approximately 1 5 needles.

Assembly The pre-assembled actuator assembly and yarn feeders assembly are mounted on the knitting machine. The pivotal position of the base plate 10 is adjusted by stop screws to locate the feeders 14 in the feed position at the distance from the needles as shown in Figure 8. The Bowden cables are attached to interconnect the assemblies. The socket 46 are adjusted to locate the feeders 14 in the rightmost adjusted feed position. The feeders 14 are then swung to the park positions and the screws 54 adjusted to engage and locate the feeders 14 in the desired park positions appropriately spaced. The feeders 14 can then be returned to the feed positions as indicated by line F. In any adjusted position the feeders 14 will be stopped by the screws 54 and the springs 50. The feeders 14 are arranged to lie just over the sinkers in the feed position as shown in Figure 8.No further adjustment is necessary.

Use The feeders 14 can be freely adjusted to take up stretch etc. in the Bowden Cables or adjust the feed position without consequential changes in the park and trap positions.

Advantages The actuator assembly and feeder assembly can be simply interconnected and require no prolonged adjustment. Manufacturing tolerances of the cams 31 are less critical. Variations may influence the extent by when one feeder leads another during change-over or the dwell period upstream of the feeder portion. The park and trap positions do not require any compensating adjustment. As the feeders perform their crossover operation upstream of the feed position, yarns from the feeders crossing over continue to be knit during the operation giving a long continuous pick up which can vary to some extent either deliberately as a result of adjustment or as a result of manufacturing tolerances without influencing the quality of the join between ingoing and outgoing yarns.

The aforementioned benefits can be obtained whilst also enabling more feeders to be incorporated than previously. Even though six feeders are employed they can at the same time be made to move through a low level during change-over for a considerable common arc of movement, preserving proper pick up conditions; yet the total arc can be kept within the confines necessary for feeding in the park position and the avoidance of wrapping yarn around other feeders.

At least two of the feeders may be bulky plating feeders.

Congestion in the knitting zone is avoided.

Sinkers and verge bits may be used as shown in Figure 8. The latchguard can be solid and utilise a small V-shaped recess. The large arc of maximum feeder movement permits the same cams to give rise to different feeder movement by varying the leverage.

The incidence of loose yarn ends on the outside of socks can be reduced. Change-over speeds may be increased. The presence of float stitches does not require re-timing or re-design as there is a long continuous pick up and a proper join will be obtained even if a group of low inactive needles do not participate in picking up the new yarn.

Advantages of the invention as described also apply to rib knitting. The feeders 14 when in the trap position are relaxed and not in contact with the cams 31 reducing wear.

Claims (9)

1. Double cylinder knitting machine having a plurality of pivotable feeders with yarn feeding ends movable through arcs from a trap position, through a feed position to a cross-over park position upstream of the feed position and a plurality of rotatable cams and cam followers connected to feeders to impart pivotal movement thereto during a feeder change and means for adjusting the feed positions of the respective feeders, in which the cams and cam followers pivot the feeders upstream of the feed position to an extent sufficient to clear a latchguard and sinkers of the knitting machine before further pivotal movement for cross-over and reaching of the park position, stop means arrest the feeders in predetermined park positions whilst the cam followers are still on an inclined part of the cams and means are provided for making continued motion of the cams ineffective after the feeders have reached the park positions.

2. Double cylinder knitting machine according to claim 1 in which from 5 to 7 feeders are arrested by the stop means.

3. Double cylinder knitting machine according to claim 1 or claim 2 in which the followers are connected to the feeders by Bowden cables, the length of the cables is adjustable to compensate for changes in cable length and to adjust the feeder position and one end of a sleeve of the cable is supported by resilient means which constitute the means for making excessive cam induced motion ineffective after the feeders have reached the park positions as a result of travelling up a cam slope.

4. Double cylinder knitting machine according to claim 3 in which stop means are provided to arrest the feeders in predetermined trap positions, excess motion being avoided by lifting the followers off the cams.

5. Double cylinder knitting machine according to claim 2 or claim 3 in which the cams and cam followers for at least some of the feeders are the same and the park and trap positions are differentiated by applying a different leverage from the cam followers to the Bowden cables.

6. Double cylinder knitting machine according to any of the preceding claims in which the feed position is adjacent the level of the upper edge of sinkers of the knitting machine and a guide plate is provided for lifting feeders for cross-over after they have moved clear of the latchguard and sinkers.

7. Double knitting machine according to claim 6 in which the feeders having park positions nearer the feed position are arranged to be lowered after the initial lifting just before reaching the respective park positions so as to be at the original feed level and at least one feeder having a park position more remote from the feed position is arranged to be moved upward just before reaching its respective park position.

8. Double cylinder knitting machine according to claim 7 in which the feeder parked nearest the feed position is a plating feeder suitable for plating in either direction of reciprocation and the feeder is arranged to be kept at the same level to move into the park position.

9. Double cylinder knitting machine substantially as shown and as described with reference to the drawings.